<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0px;
            padding: 0px;
        }
        #p {
            width: 300px;
            height: 300px;
            background-color: #4288ce;

        }

        #s {
            width: 200px;
            height: 200px;
            background-color: lime;
            padding-top: 20px;
        }
    </style>
</head>
<body>
    <div id="p">
        <div id="s">

        </div>
    </div>
</body>
</html>